# checkstr = input('请输入要判断的字符：\n')
# flag = teue
# low = 0
# high = len(checkstr) - 1
# while low < high:
#     if checkstr[high]:
#         flag = false
#         break
#     low += 1
#     high -= 1
# if flag:
#     print('“{}”是回文串。'.format(checkstr))
# else:
#     print('"不是回文串。'.format(checkstr))
#
#
#
# strs = 'rain falls   on field and tree.'
# print(strs)
# split_strs = strs.split()
# print(split_strs)
# join_strs = ''.join(split_strs)
# prin(join_strs)